Cell Theory: History and Principles
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Questions and Answers

Which of the following best explains the significance of Virchow's work in the context of cell theory?

  • He invented the first microscope, enabling the visualization of cells.
  • His endorsement of the concept that cells arise from pre-existing cells increased its acceptance within the scientific community. (correct)
  • He discovered that all living organisms are composed of cells.
  • He was the first to describe the process of cell division.

According to modern cell theory, what must occur before a pre-existing cell can give rise to fully functioning daughter cells?

  • The cell's DNA must replicate to ensure each daughter cell receives a complete set of genetic instructions. (correct)
  • The cell must establish connections with other cells to form tissues.
  • The cell must increase in size to accommodate new organelles.
  • The cell must undergo differentiation to specialize its function.

Which observation provides the strongest evidence for the principle that all living things are composed of cells?

  • The presence of similar DNA sequences across different species.
  • The discovery of atoms and molecules in non-living materials.
  • The identification of complex chemical reactions occurring in both living and non-living systems.
  • The consistent finding that all examined biological specimens, from bacteria to plants, are made up of cells. (correct)

A scientist observes a new type of cell dividing by mitosis. Based on the principles of cell theory, what can they conclude about this new cell?

<p>It originated from a pre-existing cell. (B)</p> Signup and view all the answers

Why is a rock not considered a living organism according to the first principle of cell theory?

<p>Rocks are not made up of cells. (A)</p> Signup and view all the answers

Considering the modern interpretations of cell theory, which of the options would be the LEAST likely?

<p>Cells can spontaneously generate from non-cellular material under specific environmental conditions. (A)</p> Signup and view all the answers

How does the observation that chimpanzees and humans share 98.8% of their DNA relate to cell theory?

<p>It supports the idea that closely related species have cells with very similar composition. (A)</p> Signup and view all the answers

Which of the following best summarizes the core tenets of classical cell theory?

<p>Cells are the basic units of life, all living organisms are composed of cells, and cells arise from pre-existing cells. (A)</p> Signup and view all the answers

How did Anton van Leeuwenhoek contribute to the development of cell theory?

<p>He discovered 'animalcules' (bacteria) using his self-made microscope, observing them in dental scrapings. (D)</p> Signup and view all the answers

What was the significance of Robert Hooke's observations in the context of cell theory?

<p>Hooke coined the term 'cell' after observing cell-like compartments in cork, which contributed to the naming of cells. (B)</p> Signup and view all the answers

How did the work of Matthias Schleiden and Theodor Schwann contribute to the formation of cell theory?

<p>They independently concluded that all plant and animal tissues are composed of cells, establishing a universal building block for life. (C)</p> Signup and view all the answers

What was the disagreement between Matthias Schleiden and Theodor Schwann regarding cell formation?

<p>Schleiden believed cells arose via spontaneous generation, and Schwann thought they came from other cells. (C)</p> Signup and view all the answers

How did Rudolf Virchow contribute to cell theory?

<p>By disproving spontaneous generation and stating that cells arise only from pre-existing cells. (D)</p> Signup and view all the answers

Which of the following statements reflects the progression of understanding of cell formation within cell theory?

<p>Initially, it was believed that cells arose spontaneously, but later experiments proved they only come from pre-existing cells. (C)</p> Signup and view all the answers

Why is the invention of the microscope considered a critical development in the history of cell theory?

<p>It allowed scientists to directly observe cells and their components, leading to the realization that all living things are made of cells. (D)</p> Signup and view all the answers

Flashcards

Scientific Theory

A widely accepted explanation of natural phenomena, supported by a large body of evidence that may evolve with new discoveries.

Cell Theory

A fundamental biological principle explaining the role of cells in living organisms.

Classical Cell Theory

  1. Cells are the basic unit of life. 2. All living things are made of cells. 3. Cells come from other cells.

Anton Van Leeuwenhoek

Observed 'animalcules' (bacteria) using his microscope.

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Robert Hooke

Coined term 'cell' after observing chambers in cork.

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Matthias Schleiden

Concluded that all plants are made of cells.

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Theodore Schwann

Concluded that all animals are made of cells.

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Rudolf Virchow

Proposed cells arise from pre-existing cells, not spontaneous generation.

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Cell Theory: Principle #1

Cells are the fundamental units of life and the building blocks of living organisms.

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Cell Theory: Principle #2

All living organisms are composed of one or more cells. This includes both unicellular and multicellular organisms.

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Cell Theory: Principle #3

All cells arise from pre-existing cells through cell division (mitosis or meiosis).

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Cell Theory: Genetic Information

Genetic information (DNA) is passed from parent cells to daughter cells during cell division, ensuring continuity of traits.

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Cell Theory: Similar Species

Closely related species exhibit cells with similar composition and structure due to shared genetic heritage.

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Cell Theory: Energy Flow

Cells facilitate energy flow through various metabolic processes, such as photosynthesis or cellular respiration.

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Cell Theory: Genetic Instructions

Cells contain genetic instructions, typically in the form of DNA, that dictate their structure, function, and behavior.

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Study Notes

  • Cell theory is a widely accepted explanation of the role of cells in living things.
  • Classical and modern versions of cell theory exist.

Classical Cell Theory

  • Cells are the basic unit of life.
  • All living things are made of cells.
  • Cells come from other cells.

History of Cell Theory

  • The invention of the microscope was critical to the development of cell theory.
  • Anton Van Leeuwenhoek observed microorganisms he called "animalcules" using his microscope in the 1600s.
  • Robert Hooke coined the term "cell" after observing chambers in cork that resembled monastery rooms.
  • Matthias Schleiden concluded that all plants are made of cells.
  • Theodore Schwann came to the similar conclusion that all animal samples he studied were made of cells.
  • Schleiden believed in free cell formation, or spontaneous generation.
  • Schwann believed cells came from preexisting cells.
  • Rudolf Virchow supported Schwann's idea and contributed his expertise, leading to wider acceptance of cells coming from other cells.

Three Principles of Cell Theory

Cells are the Basic Unit of Life

  • Cells are the building blocks of living things.
  • Atoms and molecules must form a cell for something to be considered living.
  • Cells combine to form tissues and organs, contributing to the overall function of an organism.

All Living Things are Made of Cells

  • Living things can be unicellular, containing a single cell, or multicellular, containing many cells.
  • Bacteria are unicellular organisms.
  • Plants, animals, and other organisms are multicellular.

Cells Come From Other Cells

  • New cells arise from cell division (mitosis and meiosis) of preexisting cells.
  • Sexual reproduction involves the formation of sperm and egg cells through cell division.
  • Organism growth stems from the division of a zygote formed from a sperm and egg cell.
  • New cells also help with tissue repair.

Modern Interpretation of Cell Theory

  • Additional discoveries led to more principles that contributed to cell theory, like:
  • Genetic information is passed to new cells during cell division.
  • Similar species contain cells of extremely similar composition.
  • Energy flows within cells.
  • Genetic instructions, often in the form of DNA, are stored in cells.
  • DNA replicates before cell division to ensure each new cell has a full set of instructions.
  • Closely related species have more similarly structured cells.
  • Chimpanzees and humans share 98.8% of their DNA, resulting in similar cells.
  • Cells can carry out their own energy flow processes, such as photosynthesis in plant cells.

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Explore the classical and modern versions of cell theory, which explain the role of cells in living organisms. Learn about key figures like Leeuwenhoek, Hooke, Schleiden, Schwann, and Virchow, and their contributions to understanding the basic unit of life. Understand how cells arise from pre-existing cells.

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